For example, in a test mode such as the 10 mode, LA-4 mode, EC mode and the like, which are respectively used in Japan, the United States, and Europe, one or more running patterns is determined for measuring fuel consumption, and there has been known a speed control device for controlling an accelerator and a brake of a vehicle (in particular, an automobile) so that an actual vehicle speed may follow a demand vehicle speed indicated in the running pattern of a test mode.
In such a conventional speed control device, an accelerator pedal and/or a brake pedal of a vehicle disposed on a chassis dynamo is operated by an amount according to a deviation between an actual vehicle speed and a demand vehicle speed so as to render the actual vehicle speed to follow the demand vehicle speed. However, in this speed control device, since a feedback control of the accelerator or the brake is selectively performed almost like a person, it is necessary to determine switching timing of the controls.
Therefore, conventionally, for example, timing of switching from a vehicle speed feedback control by operating an accelerator to a vehicle speed feedback control by operating a brake is set to a time point when the actual vehicle speed is higher than the demand vehicle speed and the vehicle is in a situation that the actual vehicle speed has to be decelerated and when an accelerator opening degree becomes 0 (i.e., accelerator is in a fully closed position), and it is configured that the vehicle speed feedback control is switched to the vehicle speed feedback control by operating the brake at this time point.
Meanwhile, the timing of switching from a vehicle speed feedback control by operating a brake to a vehicle speed feedback control by operating an accelerator is also similar, although reverse, to the above case. That is, the switching timing thereof is set to a time point when the actual vehicle speed is lower than the demand vehicle speed and the vehicle is in a situation that the actual vehicle speed has to be accelerated and when a brake depressing degree becomes 0 (i.e., brake is in an effective beginning position), and it is configured that the vehicle speed feedback control is switched to the vehicle speed feedback control by operating the accelerator at this time point.
In addition, as disclosed in Patent Literature 1, there is a known configuration of determining which of an accelerator or a brake should be controlled by comparing a demand horsepower and an actual horsepower.